The present invention relates to a device package, such as an electronic system package, that is suitable for use in harsh military or commercial environments. The package components, including a base enclosure and mating cover, comprise a series of interconnected electrically conductive materials, forming a tortuous electrically conductive path, that advantageously shield electromagnetic interference (“EMI”). The electrically conductive, EMI-shielding layers and other coated layers (e.g., insulative electrocoated paint layers) are smooth layers that provide corrosion resistance to the interior and exterior surfaces of the package. The package is also designed such that its components form a water tight seal. Thus, innovatively, the package comprises a combination of components that synergistically shield electromagnetic interference, resist interior and exterior corrosion, and form a water tight seal. The package is configured to pass military specification EMI and salt fog standard testing.